Slide switch with improved movable contact actuator resilient biasing means

ABSTRACT

An electrical switch including an insulative casing having fixed contacts and a plunger element movable within the casing having contacts for slideably engaging the fixed contacts so as to provide a plurality of switching positions. The plunger element has a plurality of oppositely disposed recesses in the sidewalls thereof and includes a spring-like portion positioned in each recess and molded integrally with the plunger element. Each spring-like portion has two independently acting spring elements projecting divergently outward from a back wall of the recess toward front wall portions thereof so as to outwardly bias the sliding contact positioned within each recess. An embodiment is also described in which the sliding contact is either plated or vacuum deposited onto an alternative spring configuration.

United States Patent Otterlei [54] SLIDE SWITCH WITH IMPROVED MOVABLECONTACT ACTUATOR RESILIENT BIASING MEANS [72] Inventor: Jon L. Otterlei,4704 Merilane,

Edina, Minn. 55436 [22] Filed: Jan. 4, 1971 [21] Appl. No.: 103,394

[52] US. Cl. ..200/16 C, 200/166 BE [51] Int. Cl. ..H0lh 15/06 [58]Field of Search ....200/16 C, 16 D, 153, 166 BE,

200/166 BF, ll K, ll J, 166 RH [56] References Cited UNITED STATESPATENTS 3,403,236 9/1968 Zoludow ..200/172 R x 3,399,282 8/1968Nagashima et al ..200/16 D 2,966,560 12/1960 Gluck ..200 16 c 3,218,40111/1965 R0012 .....200/166 BE 2,337,809 12/1943 Gaynor ..200/153 w 1451Sept. 26, 1972 Primary Examiner-J. R. Scott Attorney-Merchant & Gould [57] ABSTRACT An electrical switch including an insulative casing havingfixed contacts and a plunger element movable within the casing havingcontacts for slideably engaging the fixed contacts so as to provide aplurality of switching positions. The plunger element has a plurality ofoppositely disposed recesses in the sidewalls thereof and includes aspring-like portion positioned in each recess and molded integrally withthe plunger element. Each spring-like portion has two independentlyacting spring elements projecting divergently outward from a back wallof the recess toward front wall portions thereof so as to outwardly biasthe sliding contact positioned within each recess. An embodiment is alsodescribed in which the sliding contact is either plated or vacuumdeposited onto an alternative spring configuration.

5 Claims, 8 Drawing Figures '1 sums swrrcn wmr IMPROVED MOVABLE CONTACTACTUATOR RESILIENT BIASING MEANS BACKGROUND OF THE INVENTION forslideably engaging the fixed contacts is known in the art. Further, itis well known that such switches can .be readily miniaturized and thatsuch miniaturization :has given rise to extensive application thereof.For instance,'switches of this type can be used as wavechange switchesin' portable and car radio sets, in tape recorders, in measuring,testing and other instrument s, and especially inv telecommunicationtoperform the switching of weak-current circuits of high or lowfrequency. w

Generally, the quality of electrical switches of the above-describedtype is gauged by'the lowness and constancy of the contact resistance.In order to obtain a constant, low value contact resistance, the tensionor pressure between the fixed contacts and the sliding contacts must bewell balanced and constant.

In the prior art, a balance has been sought between providingtime-stable low contact-resistance and an inexpensive switch which isreadily manufactured and assembled. The prior art switches have not,however, satisfactorily'provided a combination of these features. Forinstance, acoil spring has commonly been utilized to influence thesliding contact outward from the sidewall of the plunger elementso as toprovide engagement thereof with the fixed electrical terminals carriedby the insulative casing. While providinga generally well-balancedcontact pressure, insertion of this extremely smallcoil spring has; beenexceedingly difficult I and, 'to obtain high volume production requiresa large investment in automatedequipi'nent. Alternatively, the springbias for the sliding contact has been achieved by utilizing a contactelement having resilient material forming at least a portion thereof-anddesigned so as to provide an outward bias,to the contact. While suchsliding contacts are inexpensive .to

manufacture, they generally do not have a stable, wellbalanced contactpressure.

SUMMARY OF THE INVENTION The present invention provides electricalswitching apparatus in which a plunger element is rhoveable within aninsulative electrical casing to provide a plurality of switchingpositions. The plunger element includes a spring-like portion formedintegrally with the element and positioned in ,a recess formed in asidewall of the plunger.

More particularly, a plurality of recesses in the plunger element areprovided each having a springdike portion positioned therein. Thespring-like portions each extend from a back wall of the respectiverecess toward front'wall portions thereof. In one preferred embodiment,an electrical contact is engaged adjacent its opposite ends by thespring-like portion andis urged laterally outwardly thereby so as toslideably coact with adjacent ones of the electrical contacts carried bythe insulative casing. In this embodiment, each spring-like 2 portionprovides two independently acting resilient strips of a plastic materialhaving adjacent end portions in a diverging relationship. In analternative embodiment, each spring-like portion includes two divergent,independently acting spring elements which are integrally connected by acurved center portion onto which the sliding contact is plated or vacuumdeposited.

The above-described electrical switching apparatus is inexpensive,readily manufactured, andyet highly reliable. By forming(e.g. molding)the biasing spring as an integral part of the plunger element, the totalnumber'of components is reduced and assembly of the switching apparatusis greatly simplified. The additional tooling cost to mold the biasingspring as a portion of the plunger is negligible; however, theachievement of almost fully automated assembly is commerciallysignificant. Further, the present switching apparatus provides lowelectrical resistance between the switching contacts and maintains thislow resistance over extended periods of operation.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings, whereinlike numerals represent like elements of the invention throughout theseveral FIGS:

FIG. 1 is a perspective view of an inverted plunger element inaccordance with the present invention;

FIG. 2 is a perspective view of the assembled switching apparatusprovided by the present invention including an insulative casing and theplunger element illustrated in Fig. l in engagement therewith;

FIG. 3 is a cross-sectional view of the plunger element along the planarsection 3-3 of FIG. 1;

FIG. 4is a cross-sectional view of the plunger element along the planarsection 4-4 of FIG. I;

, FIG. 5 is a cross-sectional 'viewof the assembled switching apparatusgenerally along the irregular section line 5-5 of FIG. 2;

FIG. 6 is a cross-sectional view of the assembled switchingapparatusalong the planar section 6-6 of Fig. 2;

FIG. 7 is a fragmented top view of a plunger element having analternative spring biasing portion and sliding contact assembly; and

FIG. 8 is a cross-sectional view of the alternative plunger elementalong the planar section 8-8 of Fig. 7.

BRIEF DESCRIPTION OF THE INVENTION In the drawings and with referenceparticularly to Figs. 1-6, electrical switching apparatus, generallydesignated 10, includes an elongated selector or plunger element. 12 andan insulative housing or casing 14, Plunger element 12 has a generallyrectangular axial cross-section and includes oppositely disposed top andbottom surfaces 20 and 21, respectively, and oppositely disposedfirstand second sidewalls 24 and 25, respectively. A center section 26extends longitudinally from a forward end 27 toward a rearward end 28. A

portion of center section 26 projects slightly vertically outward frombottom surface 21.

Plunger 12 is molded to provide a first pair of oppositely disposedopenings or recesses 30a and 30b in sidewalls 24 and 25, respectively. Asimilar pair of recesses 30c and 30d are longitudinally spaced along 5the respective sidewalls from recesses 30a and 30b Each pair of recessesis symmetrically positioned on opposite sides of the center section 26and each recess is defined by front, side and rear wall portions.

Since all the recesses are generally identical, only one such recessneed be described in detail. To illustrate, recess 30a is defined by alongitudinally extending rear wall in the form of center section 26,laterally extending sidewalls 32 and 33, and two longitudinallyextending flange portions 34 of plunger sidewall 24. Flange portions 34define the front wall portion of the recess 30a. As illustrated, flangeportions 34 define an opening in the sidewall so that recess 30a extendsfrom center section 26 to open laterally outward at sidewall 24.

' As can be seen particularly well in Figs. 1 and 6, plunger element 12has generally-similar, spring-like portions 40a-40d molded integrallytherewith and extending outwardly from center section 26 toward thefront wall portions of recesses 30a-30d, respectively. Forpurposes ofconvenience, only spring-like portion 30a is described in detail. Asillustrated, spring-like portion 30a of plunger 12 has two independentlyacting resilient strips 41 and 42 having adjacent end portionsintegrally connected to a connector portion 43 carried by center section26. The resilient strips 41 and 42 extend laterally outward towardflange portion 34 in a divergent relationship.

As can be seen in Fig.6, a plurality of similar electrical contacts50a-50d are positioned within the recesses 30a-30, respectively, betweenthe respective springlike portion 40a-40d and flange portions 34 ofplunger 12. Each of the contacts (e.g. contact 50a) includes oppositelydisposed generally planar end portion 51 and 52 and a laterallyoutwardly curved center portion 53v extending therebetween. End portions51 and 52 are engaged'by an outer portion of the independently actingresilient strips 41 and 42, respectively, and the resilient-strips urgethe respective end portions 51 and 52 laterally outward toward theflange portions 34 for engagement therewith.- In this position, thecurved center portion 53 of each of the sliding contacts protrudeslaterally outward from the openings in the sidewall ofplunger 12 definedby flange portions 34.

Although not critical to the present invention, male plunger 12 ispreferably molded to provide notched sections 60 and 61 in the wallsthereof. As will be subsequently described, notched sections 60 and 61are utilized to maintain plunger 12 in a fixed switching position. Acollar portion.62 of plunger 12 engages a coil spring 63 extendingbetween collar 62 and a rearward end 6 4 of casing 14 so as to urgeplunger 12 outwardly therefrom. Utilization of coil spring 63 allowsoperation of switch as a momentary action switch. Normally, a knob orbutton (not shown) is attached to rearward end 28 of plunger 12 foraiding manual move ment of the plunger within casing 14.

' The elongated insulative housing or casing 14 is preferably formed bya channel-like lower portion 70 and a top surface or cover 72 secured tochannel-like portion 70 so as to form a unitary casing. A plurality ofspaced electrical contacts or terminals 80 and 82 are carried by casing14. The terminals extend vertically through casing 14 along the innervertical walls defining channel-like portion 70. As illustrated, theelectrical terrnainsl 80 and 82 are provided with an upper end suitablefor use as a solder lug and a lower spiked end suitable for mounting theswitching apparatus onto a printed circuit board. Other terminal designscan, however, be utilized. A longitudinally extending groove 84 inchannel-like portion receives the portion of plunger center section 26extending beyond bottom surface 21 and provides means for guidingplunger 12 therein. Casing 14 includes a slot 85 in cover portion 72 forreceiving a hook-like portion of a latch or stop member 86 which extendsdownward therethrough for engaging recessed section 61 of plunger 12. Itshould be understood that numerous modifications can be made to theinsulative casing 14 and various alternative casings presently availablecan be utilized so long as the fixed electrical contacts carried therebyare positioned so as to slidingly coact with the contacts carried by theplunger element 12. u

Plunger 12 is molded from a material which provides resiliency to thespring-like portions integrally molded therewith. However, since thespring-like portions are displaced only relatively short distances andare preferably molded in the form of thin strips, numerous materialswill provide the desired resiliency. For example, an acetalresin(Delrin, a product of E. I..Dupont de Nemours & Co.) can beutilized. The channel-like portion 70 of insulative casing 14 ispreferably formed from a thermoplastic carbonate-linked polymer (e.g.-Lexan 500, a product of General Electric Co.). Numerous other materialcan, of course, be utilized. Cover portion 72 is preferably formed fromheat resistant material so as to protect the resilient material fromdamage during the soldering of electrical leads to the terminals and 82affixed to casing 14. Numerous sufficiently heat resistant materials arecommercially available.

In its assembled position, plunger 12, including the electrical contacts50a-50d, is inserted into the casing 14. The movement of plunger-12within casing 14 is guided by the engagement of plunger center ridge 26'and longitudinal groove 84 of casing 14. Under the influence of thespring-like portions 40a-40d, the curved center portion of each slidingcontact 50a-50d is biased laterally outward from the respective plungersidewall. As illustrated, each center portion (e,g. center portion 53 ofcontact 50a has a longitudinal length sufficient to extend between anytwo adjacent terminals 80 or 82 carried by casing 14. Thus, by movingplunger 12 longitudinally toward a forward end 90 of casing 14, thecontacts 50a-50d slidingly engage or coact with adjacent ones of therespective electrical terminals 80 and 82 providing an electric circuittherebetween. I

In FIG. 6, a first switching position of plunger 12 is shown. In thisposition, the latch member 86 is inserted into longitudinal slot andprevents plunger 12 from moving longitudinally outward from rearward end64 under the bias of spring 63. To break the electrical circuit providedby plunger 12 in its first or rearward position, the plunger is pushedagainst the bias of return spring 63 toward forward end by applyingpressure to rearward end 28 of the plunger. As plunger 12 slideslongitudinally within casing 14, the spring-like portions 40a-40 allowlaterally inward movement of the respective contacts 50a-50d to preventdamage thereto and to facilitate easier movement of the plunger. In itssecond or forward position plunger 12 is maintained in such position bya conventional latch mechanism, not shown. This latch mechanism isengagable in notch 60, so that the contacts 50a-50d provide anelectrical path between other adjacent terminal pairs 80 along one wallof casing 14 and between similarly positioned other terminal pairs 82 onthe opposite wall. Pressure applied to rearward end 28, of plunger 12operates the latch mechanism in notch 60 and return spring 63 returnsplunger 12 to its first or rearward position.

In an alternative spring biasing construction illustrated in FIGS. 7 and8, parts identical to parts illustrated in FIGS. 1-6 areidentified byidentical numerals. In this alternative embodiment, a pair of springlikeportions 92 are molded so as to each include two independently actingspring elements 93 and 94 having adjacent end portions and extendinglaterally outward from connector portion 96 in a diverging relationship.A curved center portion 97 extends integrally between the outer portionsof spring elements 93 and 94. Under the influence of the spring elements93 and 94, the center portion 97 projects outward from openings in thesidewall of plunger 12 defined by the front wall portion 98 of eachrecess. The outer surface of center portion 97 is coated with aconductive material 99 (e.g. silver) so as to provide a conductive pathbetween adjacent terminals in the same manner as described previously.The conductive material 99 can be either plated or vacuum deposited ontothe center portion. As in the embodiment illustrated in FIGS. 1-6, thealternative embodiment provides a well-balanced contact pressure whichremains substantially constant over extended period of operation. Aswill be readily appreciated, this alternative embodiment furtherfacilitates assembly of the switching apparatus.

It is preferable that the spring tension applied to the sliding contactsis applied at the opposite ends thereof and that the spring tensionapplied to each end is independently acting. The spring portions ofplunger 12 shown in FIGS. 1-8 provide these features. Further, lateralmovement of the sliding contacts within the respective recesses isreadily permitted by the biasing spring portions thereby allowing theplunger element to be readily moved between different switchingpositions. However, it will be apparent to those of ordinary skill inthe art that the spring-like portion of plunger 12 can take numerousalternative shapes so long as it is formed as an integral portion of theplunger and urges the sliding contact associated therewith outwardlytowards the fixed contacts carried by casing 14 so as to coacttherewith. Since numerous modifications in the described embodimentswill be apparent to those skilled in the art, it is my intent to belimited only by the spirit and the scope of the appended claims.

What is claimed is:

1. Electrical switching apparatus, comprising:

a. an insulative casing; b. a plurality of electrical contacts fixedlycarried by said casing;

with said element and d. electrical contaci means in engagement withsaid spring-like portion of said plunger and urged laterally outwardthereby for slidingly coacting with said fixed electrical contactscarried by said insulative casing.

2. The electrical switching apparatus of claim 1 wherein:

a. said recess is defined by front, rear and sidewall portions, saidfront wall portion having an opening therein defined by a flange portionformed integrally with the plunger element sidewall; and

b. said spring-like portion extends outwardly from the rear wall of saidrecess toward the front wall portion thereof.

3. Electrical switching apparatus, comprising:

a. an insulative casing;

b. a plurality of electrical contacts fixedly carried by said casing;

c. a plunger element longitudinally moveable within said casing having arecess in at least one sidewall thereof defined by front, rear andsidewall portions in which said front wall portion includes an openingtherein defined by a flange' portion formed integrally with the plungersidewall and further having a spring-like portion positioned within saidrecess and formed integrally with said element so as to extend outwardlyfrom the rear wall of said recess toward the front portion thereof; and

. sliding electrical contact means having oppositely disposed planar endportions and an outwardly projecting curved center portion, saidspring-like portion urging said planar end portion toward said frontwall portion and said curved center portion toward said opening.

4. The electrical switching apparatus of claim 3 wherein saidspring-like portion includes a pair of independently acting resilientstrips having inner end portions connected to one another by a connectorportion carried by said rear wall, each of said resilient stripsextending divergently outward from said connector portion toward adifferent one of said planar end portions of said contact means.

5. The electrical switching apparatus of claim 2 wherein:

a. said spring-like portion includes a pair of independently actingspring elements extending divergently outward from said rear wall ofsaid recess toward said front wall and an outwardly curved portionextending between the outer portions of said spring elements andintegrally connected thereto; and

b. said'sliding electrical contact is carried by said outwardly curvedportion.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 694'5Q I Dated September 26, 1972 Inventor(s) Jon L. Otterlei 7 It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are herebycorrected as shown below:

Column 2,- line 2, after "portions" insert and extending toward thefront wall portions-;

Column 3, line 32, "30" should be- ---30d;

Column 3,' line 35, "portion" should be -p0rtions;

Colunm 4, line 53,. "and" should be or-; and

Column 4, line 65, "40" should be -40d--.\

Signed and sealed this 10th day of April 1973'.

(SEAL) Attest: EDWARD M.FLETCHER,JR. I ROBERT GOTTSCHALK AttestingOfficer Commissioner of Patents FORM O-1050 [10-69) USCOMM-DC 6O376-P69u.s. GOVERNMENT PRINTING OFFICE: I969 03663 u,

UNITED STATES PATENT OFFICE CERTIFICATE OF Patent No. 3 94 590 DatedSeptember 26, 1972 Inventor(s) Jon L. Otterlei It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 2,- line 2, after "portions" insert --and extending toward thefront wall portions-;

Column 3, line 32, "30" should be 30d--;

Column 3, line 35, "portion" should be --portion s--;

- Column 4, line 53 "and" should be or-; and

Column 4, line 65, "40" should be -40d- Signed and sealed this 10th dayof April 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents F ORM PC1-1050 (1069) USCOMM-DC 60376-P69 1': us GOVERNMENTPRINTING OFFICE i969 mass-334,

1. Electrical switching apparatus, comprising: a. an insulative casing;b. a plurality of electrical contacts fixedly carried by said casing; c.a plunger element longitudinally moveable within said casing, saidelement having a recess in at least one sidewall thereof and aspring-like portion positioned within said recess and molded integrallywith said element; and d. electrical contact means in engagement withsaid spring-like portion of said plunger and urged laterally outwardthereby for slidingly coacting with said fixed electrical contactscarried by said insulative casing.
 2. The electrical switching apparatusof claim 1 wherein: a. said recess is defined by front, rear andsidewall portions, said front wall portion having an opening thereindefined by a flange portion formed integrally with the plunger elementsidewall; and b. said spring-like portion extends outwardly from therear wall of said recess toward the front wall portion thereof. 3.Electrical switching apparatus, comprising: a. an insulative casing; b.a plurality of electrical contacts fixedly carried by said casing; c. aplunger element longitudinally moveable within said casing having arecess in at least one sidewall thereof defined by front, rear andsidewall portions in which said front wall portion includes an openingtherein defined by a flange portion formed integrally with the plungersidewall and further having a spring-like portion positioned within saidrecess and formed integrally with said element so as to extend outwardlyfrom the rear wall of said recess toward the front portion thereof; andd. sliding electrical contact means having oppositely disposed planarend portions and an outwardly projecting curved center portion, saidspring-like portion urging said planar end portion toward said frontwall portion and said curved center portion toward said opening.
 4. Theelectrical switching apparatus of claim 3 wherein said spring-likeportion includes a pair of independently acting resilient strips havinginner end portions connected to one another by a connector portioncarried by said rear wall, each of said resilient strips extendingdivergently outward from said connector portion toward a different oneof said planar end portions of said contact means.
 5. The electricalswitching apparatus of claim 2 wherein: a. said spring-like portionincludes a pair of independently acting spring elements extendingdivergently outward from said rear wall of said recess toward said frontwall and an outwardly curved portion extending between the outerportions of said spring elements and integrally connected thereto; andb. said sliding electrical contact is carried by said outwardly curvedportion.